The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
When communication devices exchange data over wired or wireless communication channels, the medium through which the data propagates, as well as processing at intermediate or endpoint communication devices, introduce various propagation delays to the data exchange. For example, an Ethernet link connecting a pair of communication devices typically delays a communication frame by several microseconds, and the propagation delay generally depends on the length of the Ethernet link. On the other hand, a network router that receives a frame, processes the received frame, and further transmits the frame can introduce a much longer delay, typically measured in milliseconds.
Some communication protocols specify techniques for transmitting time stamp information for data units. However, a transmitting device and a receiving device may have clocks that were started at different times and that run at different rates. Accordingly, standards have been developed to allow communication devices to exchange timing and synchronization information. In particular, the Institute for Electrical and Electronics Engineers (IEEE) 802.1AS Standard specifies a protocol and procedures for synchronizing Local Area Networks (LANs). Today, Ethernet ports are synchronized using the IEEE 802.1AS Standard and the IEEE 802.3af (“Power over Ethernet”) Standard. As another example, wireless ports are synchronized using the IEEE 802.1AS Standard and the IEEE 802.11v Standard, which specifies configuration techniques for client devices connected to wireless networks.